Preparation methods of pentamethyldisiloxane and active silicone oil

Abstract

This invention provides a method for preparing pentamethyldisiloxane and an active silicone oil. The method for preparing pentamethyldisiloxane includes the following steps: 1) mixing dimethylchlorosilane with a long-chain alkylchlorosilane to obtain a mixed solution, adding the mixed solution dropwise to water, and reacting at 35-40°C for 1-2 hours after the addition is complete. After the reaction, allowing the mixture to stand and separating the layers, collecting the upper layer, and removing water and low-boiling water; 2) adding hexamethyldisiloxane to the product obtained in step 1), rearranging the mixture at 20-40°C under the action of a first catalyst, filtering, and distilling to collect the fraction obtained at 85-87°C on a 60cm Widmanstätten column; the first catalyst is concentrated sulfuric acid, a solid acid, or a cation exchange resin. The method for preparing 1,1,3,3,3-pentamethyldisiloxane provided by this invention is simple, low-cost, economical, environmentally friendly, has a high yield, and yields pentamethyldisiloxane with high purity.

Description

Technical Field

[0001] This invention relates to the field of silicone oil synthesis technology, and more specifically, to a method for preparing pentamethyldisiloxane and an active silicone oil. Background Technology

[0002] 1,1,3,3,3-Pentamethyldisiloxane (abbreviated as pentamethyldisiloxane) is an important organosilicon intermediate. This intermediate can undergo hydrosilylation reactions with other compounds containing unsaturated bonds to prepare substances with different reactive groups. It can be directly used as an end-capping agent to prepare various organosilicon polymers with inert functional groups at one end and reactive groups at the other end. Compared with double-ended reactive polymers and side-chain reactive polymers, such organosilicon polymers can endow materials with new properties, such as low surface tension, high flexibility, high water and solvent resistance, and good chemical stability. They are excellent synthetic raw materials and modifiers for rubber, resins, and other materials.

[0003] However, as a capping agent, the presence of hexamethyldisiloxane or 1,3-tetramethyldisiloxane in 1,1,3,3,3-pentamethyldisiloxane can significantly affect the performance of the synthesized organosilicon polymers. Existing methods for preparing 1,1,3,3,3-pentamethyldisiloxane primarily involve co-hydrolysis and condensation at low temperatures with equimolar amounts of dimethylethoxysilane and trimethylchlorosilane, or dimethylchlorosilane and hexamethyldisilane, or trimethylsilanol and dimethylchlorosilane. These methods yield large amounts of byproducts, 1,1,3,3-tetramethyldisiloxane and hexamethyldisiloxane, resulting in an overall pentamethyldisiloxane yield of less than 30%. Furthermore, the boiling points of 1,1,3,3-tetramethyldisiloxane and hexamethyldisiloxane are very close to those of 1,1,3,3,3-pentamethyldisiloxane, making it extremely difficult to separate the pure pentamethyldisiloxane product. These methods also place high demands on the separation equipment. Another type of method for preparing pentamethyldisiloxane involves reacting alkali metal silanoates with dimethyl halosilane compounds in an acidic system at a 1:1 molar ratio in an organic solvent. While this method can achieve separation of byproducts from the target product through solvent optimization, alkali metal silanoates are expensive and reactive, making them prone to degradation and hindering large-scale industrial production. Furthermore, existing technologies, such as CN101875662B, employ high-hydrogen-content silicone oil and Grignard reagents in solvents like toluene and ether, followed by hydrolysis to prepare pentamethyldisiloxane with a yield of approximately 50%. Although this method avoids the introduction of chlorosilanes, the high-hydrogen-content silicone oil is expensive and often obtained through the hydrolysis and condensation of chlorosilanes. Additionally, the use of Grignard reagents requires stringent conditions, and the separation and purification of the large amount of magnesium salt byproducts from the solvent and water is challenging, further hindering large-scale production. Summary of the Invention

[0004] To address, or at least partially address, the problems in the prior art, this invention provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane (also known as pentamethyldisiloxane), which effectively improves the yield and purity of the product pentamethyldisiloxane.

[0005] The present invention provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0006] 1) Mix dimethylchlorosilane with long-chain alkylchlorosilane to obtain a mixture, add the mixture dropwise to water, and react at 35-40°C for 1-2 hours after the addition is complete. After the reaction is complete, let it stand and separate the liquids. Take the upper layer and remove water and low-boiling water.

[0007] 2) Add hexamethyldisiloxane to the product obtained in step 1), rearrange it at 20-40°C under the action of the first catalyst, filter it, and collect the fraction at 85-87°C and 60cm Widmanstätten column by distillation; the first catalyst is concentrated sulfuric acid, solid acid or cation exchange resin.

[0008] In a preferred embodiment of the present invention, in order to further improve the yield and purity of the product, in step 1), the long-chain alkylchlorosilane is dimethylpropylchlorosilane, chloropropyldimethylchlorosilane, dimethylhexylchlorosilane, dimethyloctylchlorosilane, dimethyldecylchlorosilane or dimethyldodecylchlorosilane, preferably dimethyloctylchlorosilane.

[0009] In a preferred embodiment of the present invention, to further improve the yield and purity of the product, in step 1), the molar ratio of dimethylchlorosilane to long-chain alkylchlorosilane is (1.1–1.3):(1.6–2.6). In step 1), the amount of water used can be 75%–100% of the total mass of dimethylchlorosilane and long-chain alkylchlorosilane.

[0010] In a preferred embodiment of the present invention, in order to further improve the yield and purity of the product, in step 1), the dropping rate of the mixture into the water is controlled to keep the temperature of the reaction system between 20 and 25°C.

[0011] In a specific embodiment of the present invention, in step 1, a dehydrating agent such as anhydrous magnesium sulfate can be used to remove water. The "removal of low-boiling-point substances" step can specifically be: removing low-boiling-point substances at -0.03 to -0.02 MPa and 50 to 60°C.

[0012] In a preferred embodiment of the present invention, to further improve the yield and purity of the product, in step 2), the first catalyst is a solid acid, more preferably the solid acid HND-580. In this step, the amount of the first catalyst is 8-12% by mass of hexamethyldisiloxane.

[0013] In a preferred embodiment of the present invention, in order to further improve the yield and purity of the product, in step 2), the molar ratio of hexamethyldisiloxane to dimethylchlorosilane is 1:(1.1 to 1.3).

[0014] In one embodiment of the present invention, step 2) may include: adding hexamethyldisiloxane and a first catalyst to the product obtained in step 1), stirring the reaction at room temperature (e.g., 20–30°C) for 0.5–1 h, heating to 35–40°C for rearrangement reaction for 1–2 h, filtering, and then distilling to collect the fraction obtained at 85–87°C on a 60 cm Widmanstätten column. In the present invention, the collected fraction is 1,1,3,3,3-pentamethyldisiloxane.

[0015] In one embodiment of the present invention, if a liquid catalyst such as concentrated sulfuric acid is used in step 2) and the subsequent synthesis of active silicone oil, after the reaction is completed, the pH is adjusted to 6-7 by neutralizing with sodium acetate, sodium carbonate, etc., before subsequent filtration and distillation steps are performed.

[0016] Using the preparation method provided by the present invention to prepare 1,1,3,3,3-pentamethyldisiloxane, the yield can be as high as 80%, preferably as high as 85%, and more preferably as high as 89.5%, and the purity of the obtained 1,1,3,3,3-pentamethyldisiloxane can be as high as 97%, preferably as high as 98%.

[0017] The 1,1,3,3,3-pentamethyldisiloxane prepared by this invention has high purity. The preparation of active silicone oil using the 1,1,3,3,3-pentamethyldisiloxane obtained by this method is simple. The epoxy silicone oil synthesized based on this method can improve the "sudden increase" in viscosity during use when used in organic potting compounds, while keeping the strength and other performance indicators unchanged, thus improving the convenience of construction operations.

[0018] Another object of the present invention is to provide a method for preparing active silicone oil, the method comprising the following steps:

[0019] S1, the 1,1,3,3,3-pentamethyldisiloxane obtained in step 2) of the above preparation method is mixed with a cyclosiloxane, and the mixture undergoes ring-opening rearrangement under the action of a second catalyst to remove impurities; the second catalyst is concentrated sulfuric acid, trifluoromethanesulfonic acid, perfluorosulfonic acid type ion exchange resin or solid acid.

[0020] S2, under nitrogen protection, the product obtained in step S1 is mixed with a compound containing unsaturated double bonds and a third catalyst, and reacted at 60-80°C to remove impurities; the compound containing unsaturated double bonds is allyl glycidyl ether and / or 4-vinylepoxycyclohexane; the third catalyst is a ketone-amine platinum catalyst.

[0021] That is, the preparation method of this active silicone oil includes the following steps:

[0022] 1) Mix dimethylchlorosilane with long-chain alkylchlorosilane to obtain a mixture, add the mixture dropwise to water, and react at 35-40°C for 1-2 hours after the addition is complete. After the reaction is complete, let it stand and separate the liquids. Take the upper layer and remove water and low-boiling water.

[0023] 2) Add hexamethyldisiloxane to the product obtained in step 1), rearrange it at 20-40°C under the action of a first catalyst, filter, and collect the fraction at 85-87°C and a 60cm Widmanstätten column by distillation; the first catalyst is concentrated sulfuric acid, solid acid or cation exchange resin.

[0024] S1, the 1,1,3,3,3-pentamethyldisiloxane obtained in step 2) of the above preparation method is mixed with a cyclosiloxane, and the mixture undergoes ring-opening rearrangement under the action of a second catalyst to remove impurities; the second catalyst is concentrated sulfuric acid, trifluoromethanesulfonic acid, perfluorosulfonic acid type ion exchange resin or solid acid.

[0025] S2, under nitrogen protection, the product obtained in step S1 is mixed with a compound containing unsaturated double bonds and a third catalyst, and reacted at 60-80°C to remove impurities; the compound containing unsaturated double bonds is allyl glycidyl ether and / or 4-vinylepoxycyclohexane; the third catalyst is a ketone-amine platinum catalyst.

[0026] The preferred solutions for steps 1) and 2) are as described above and will not be detailed here.

[0027] In a preferred embodiment of the present invention, in step S1, the cyclosiloxane is dimethylcyclosiloxane, methylphenylcyclosiloxane, methylvinylcyclosiloxane, octamethylcyclotetrasiloxane, tris(trifluoropropyl)cyclotrisiloxane, tetramethyltetravinylcyclotetrasiloxane, trimethyltriphenylcyclotrisiloxane, or tetramethyltetraoctylcyclotetrasiloxane, preferably dimethylcyclosiloxane. In ring-opening reactions in the art, dimethylcyclosiloxane is typically a mixed cyclic form of dimethylcyclosiloxane. Commercially available mixed cyclic forms of dimethylcyclosiloxane typically contain more than 95% D4, 4-5% D5, and the remainder D3. It is well known to those skilled in the art that the molecular weight of this commercially available mixed cyclic form of dimethylcyclosiloxane is based on the molecular weight of octamethylcyclotetrasiloxane.

[0028] In one embodiment of the present invention, a liquid catalyst such as concentrated sulfuric acid is used in step S1, and after the reaction is completed, the pH is adjusted to 6-7 by neutralizing with sodium acetate, sodium carbonate, etc. before proceeding to the next step.

[0029] In a preferred embodiment of the present invention, in step S1, the second catalyst is preferably a solid acid, and more preferably solid acid YLCT-2. In a specific embodiment of the present invention, solid acid YLCT-2 purchased from Elest New Materials Technology Co., Ltd. is used as an example to describe the present invention in detail. The amount of the second catalyst is preferably 0.2% to 1.0% of the total mass of the cyclosiloxane and 1,1,3,3,3-pentamethyldisiloxane in step 3).

[0030] In a preferred embodiment of the present invention, in step S1, the molar ratio of the cyclosiloxane to the hexamethyldisiloxane in step 2) is (3-10):1, preferably (5-8):1.

[0031] In one specific embodiment of the present invention, step S1 may include: under stirring conditions, dehydrating the cyclosiloxane at 70-80°C and -0.03-0.02 MPa for 0.5-1 h, adding the pentamethyldisiloxane obtained in step 2) and the second catalyst, and reacting the ring-opening rearrangement at 70-90°C for 1-4 h, cooling and filtering, and distilling to remove low-boiling substances (distillation conditions may be -0.05-0.04 MPa and 130-140°C) to obtain the final product.

[0032] In a preferred embodiment of the present invention, in step S2, the molar ratio of the compound containing unsaturated double bonds to the raw material of hexamethyldisiloxane (step 2) is (0.9-1):1.

[0033] In a preferred embodiment of the present invention, the third catalyst is preferably triphenylphosphine platinum. Specifically, the triphenylphosphine platinum is preferably a platinum compound with high steric amine coordination obtained by reacting chloroplatinic acid with 2,6-diisopropylaniline and acetylacetone (molar ratio can be 1:(1-2):(1-2)). The preferred method for preparing the triphenylphosphine platinum used in the present invention includes the following steps: mixing 2,6-diisopropylaniline with acetylacetone and isopropanol, micro-refluxing for 10-15 h, cooling to room temperature, cryogenic filtration, mixing the solid with a tetrahydrofuran solution of chloroplatinic acid, reacting at 60-65°C for 1.5-2 h, recrystallizing with dichloromethane, and drying. The molar ratio of chloroplatinic acid to 2,6-diisopropylaniline and acetylacetone is 1:(1-2):(1-2).

[0034] In a preferred embodiment of the present invention, the additive for the third catalyst is preferably such that the Pt content in the system of step S2 is 20 to 100 ppm.

[0035] In a preferred embodiment of the present invention, step S2 may include: under nitrogen protection, activating the compound containing unsaturated double bonds with a third catalyst at 50-60°C for 0.5-1 h, adding the product of step S1 dropwise, reacting at 60-80°C for 2-3 h after the addition is complete, slowly raising the temperature to 130-150°C, and blowing in dry nitrogen to remove low-boiling substances (distillation conditions can be -0.03 MPa to -0.02 MPa, 100-110°C) to obtain the product.

[0036] The method for preparing single-ended active silicone oil provided by this invention is simple, suitable for large-scale production, has high yield and low cost. The active silicone oil obtained can be used in organosilicon potting compounds with significantly reduced "stickiness" and improved ease of construction without changing the strength and other performance indicators.

[0037] Another object of the present invention is to provide an active silicone oil obtained by the above preparation method.

[0038] The beneficial effects of this invention are as follows:

[0039] 1) A method for preparing 1,1,3,3,3-pentamethyldisiloxane is proposed. This method is simple, low-cost, economical, environmentally friendly, and has a high yield (up to 90%), yielding pentamethyldisiloxane with high purity (up to 98%). Based on this, epoxy silicone oils with arbitrary molecular weight and epoxy group content can be prepared.

[0040] 2) A method for preparing active silicone oil is proposed. Based on the high yield and high purity of pentamethyldisiloxane, the method for preparing active silicone oil provided by this invention is economical, environmentally friendly, and low in cost. The active silicone oil obtained has a hydrogen content of 0.025-0.06% and a viscosity of 20-60 mPa·s. That is, the preparation method provided by this invention can efficiently (high hydrosilylation efficiency, epoxy value close to the theoretical value) obtain active silicone oil with an epoxy value of (0.025-0.055) mol / 100g and a viscosity of 20-60 mPa·s, greatly improving the convenience of using this type of active silicone oil in actual production. Detailed Implementation

[0041] The specific embodiments of the present invention will be further described in detail below with reference to the examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention. In the present invention, unless otherwise specified, "%" refers to a mass percentage. In the specific embodiments of the present invention, solid acid HND-580 was purchased from Jiangyin Nanda Synthetic Chemical Co., Ltd., and solid acid YLTC-2 was purchased from Elest New Materials Technology Co., Ltd.

[0042] Example 1

[0043] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0044] (1) At room temperature, a mixture of 74.5 g of dimethyl octylchlorosilane and 22.7 g of dimethyl monochlorosilane was added dropwise to 78 g of water. The temperature of the system was controlled between 20 and 25 °C. After the addition was complete, the temperature was raised to 38 °C and kept at that temperature for 1 h. The mixture was allowed to stand and separated. The upper layer was taken, and 10.2 g of anhydrous magnesium sulfate was added. After drying, the mixture was filtered and distilled at -0.03 to -0.02 MPa at 58 °C until no bubbles were generated, thus obtaining the product.

[0045] (2) Add 32.5g of hexamethyldisiloxane and 3.3g of catalyst solid acid HND-580 to the product of step (1) and stir at room temperature (22-25℃) for 0.5h. Then raise the temperature to 36℃ and react for 1.5h. Filter and collect 26.8g of 1,1,3,3,3-pentamethyldisiloxane with a gas chromatographic content of 98.2% (i.e., purity) by distillation at 85-87℃ and 60cm Widmanstätten column. The yield is 90.3% (in this embodiment of the invention, the yield is calculated based on the amount of hexamethyldisiloxane without excess, as hexamethyldisiloxane provides the trimethylsiloxy group in the pentamethyldisiloxane molecular chain).

[0046] The 1H NMR spectrum data of 1,1,3,3,3-pentamethyldisiloxane obtained in this embodiment are as follows: 1 H-NMR (400MHz, CDCl3, δ): 0.02ppm (9H, Si CH3 ),0.08ppm(6H,SiCH3),4.52(1H,SiH).

[0047] Example 2

[0048] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, which is the same as that in Example 1, except that: in step (1), the long-chain alkylchlorosilane is 0.36 mol of dimethylpropylchlorosilane and 68 g of water; in step (2), the first catalyst is 3.3 g of concentrated sulfuric acid; and step (2) also includes adjusting the pH of the system to 6.12 with sodium acetate after the reaction is completed, then filtering, and then distilling at 85-87℃ on a 60 cm Widmanstätten column.

[0049] The yield of 1,1,3,3,3-pentamethyldisiloxane obtained in this embodiment was 89.1%, and the purity (i.e., gas chromatographic content) was 98.3%.

[0050] Example 3

[0051] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, which is the same as that in Example 1, except that: in step (1), the long-chain alkyl chlorosilane is 0.36 mol of dimethyldecyl chlorosilane and 86 g of water; in step (2), the first catalyst is 3.3 g of NKC-9 cationic resin.

[0052] The yield of 1,1,3,3,3-pentamethyldisiloxane obtained in this example was 87.6%, and the purity was 97.8%.

[0053] Example 4

[0054] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0055] (1) At room temperature, a mixture of 103.4 g of dimethyloctylchlorosilane and 24.6 g of dimethylmonochlorosilane was added dropwise to 128 g of water. The temperature of the system was controlled between 20 and 25 °C. After the addition was complete, the temperature was raised to 40 °C and kept at that temperature for 2 h. The mixture was allowed to stand and separated. The upper layer was taken, anhydrous magnesium sulfate was added and dried, and then filtered. The mixture was distilled at -0.03 to -0.02 MPa and 58 °C until no bubbles were generated, and the product was obtained.

[0056] (2) Add 32.5g of hexamethyldisiloxane and 3.9g of catalyst solid acid HND-580 to the product of step (1) and stir at room temperature (22-25℃) for 0.5h. Then raise the temperature to 40℃ and react for 2h. After filtration, collect 26.6g of 1,1,3,3,3-pentamethyldisiloxane with a gas chromatographic purity of 98% by distillation at 85-87℃ and 60cm Widmanstätten column, with a yield of 89.8%.

[0057] Example 5

[0058] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0059] (1) At room temperature, a mixture of 62.1 g of dimethyloctylchlorosilane and 19.9 g of dimethylmonochlorosilane was added dropwise to 82 g of water. The temperature of the system was controlled between 20 and 25 °C. After the addition was complete, the temperature was raised to 40 °C and kept at that temperature for 2 h. The mixture was allowed to stand and separated. The upper layer was taken, anhydrous magnesium sulfate was added and dried, and then filtered. The mixture was distilled at -0.03 to -0.02 MPa and 58 °C until no bubbles were generated, and the product was obtained.

[0060] (2) Add 32.5g of hexamethyldisiloxane and 2.3g of catalyst solid acid HND-580 to the product of step (1) and stir at room temperature (22-25℃) for 0.5h. Then raise the temperature to 40℃ and react for 2h. After filtration, collect 26g of 1,1,3,3,3-pentamethyldisiloxane with a gas chromatographic purity of 97.9% by distillation at 85-87℃ and 60cm Widmanstätten column, with a yield of 87.5%.

[0061] Example 6

[0062] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0063] (1) At room temperature, a mixture of 115.8 g of dimethyloctylchlorosilane and 26.5 g of dimethylmonochlorosilane was added dropwise to 171 g of water. The temperature of the system was controlled between 20 and 25 °C. After the addition was complete, the temperature was raised to 40 °C and kept at that temperature for 2 h. The mixture was allowed to stand and separated. The upper layer was taken, anhydrous magnesium sulfate was added and dried, and then filtered. The mixture was distilled at -0.03 to -0.02 MPa and 58 °C until no bubbles were generated, and the product was obtained.

[0064] (2) Add 32.5g of hexamethyldisiloxane and 4.9g of concentrated sulfuric acid to the product of step (1), stir and react at room temperature (22-25℃) for 0.5h, raise the temperature to 40℃ and react for 2h, wash with water until pH 6.4, filter, and collect 24.8g of 1,1,3,3,3-pentamethyldisiloxane with a gas chromatographic purity of 98.2% and a yield of 83.6% by distillation at 85-87℃ and 60cm Widmanstätten column.

[0065] Example 7

[0066] This embodiment provides a method for preparing active silicone oil, including the following steps:

[0067] (3) 296.6g of DMC dimethylcyclosiloxane mixed ring (1 mol based on octamethylcyclotetrasiloxane) was mixed with 36.8g of the product 1,1,3,3,3-pentamethyldisiloxane obtained in step (2) of Example 1 and 1.4g of catalyst perfluorosulfonic acid resin (purchased from Shanghai Hancheng Industrial Co., Ltd. (Hancheng Technology)). The mixture was reacted at 80℃ for 2.5h, cooled, filtered, and distilled at -0.04 to -0.03MPa and 140℃ to remove bubbles until no bubbles were found, yielding 326.4g of product.

[0068] (4) 21g of allyl glycidyl ether was activated with a third catalyst (the amount of the third catalyst was such that the Pt content in the system of step (4) was 30ppm) at 55℃ for 0.5h. The product of step (3) was added dropwise. After the addition was complete, the mixture was kept at 72-75℃ for 2h. The mixture was then distilled at -0.05MPa to -0.04MPa and 80℃ until no bubbles were observed. The mixture was cooled, and 5g of dry activated carbon was added. The mixture was heated to 70℃ and stirred for 0.5h. After cooling and filtration, 346.1g of colorless and transparent liquid, i.e., activated silicone oil, was obtained. The epoxy value was tested to be 0.054mol / 100g. The epoxy value of this invention was obtained according to GB / T 1677-2008, and the viscosity was tested using a Brookfield DV2T viscometer.

[0069] The synthesis steps of the third catalyst are as follows:

[0070] 0.5 g of 2,6-diisopropylaniline, 0.28 g of acetylacetone, and 10 ml of isopropanol were added to a 50 ml three-necked flask. The mixture was heated to 80 °C and refluxed gently for 15 h. After cooling to room temperature, the mixture was cryogenically cooled to -20 °C and filtered. The solid powder was then mixed with a tetrahydrofuran solution of 1.4 g of chloroplatinic acid hexahydrate and subjected to a coordination reaction at 65 °C for 2 h. After the reaction was completed, the mixture was recrystallized from dichloromethane and dried to obtain an orange-yellow powdered catalyst.

[0071] Experimental Example

[0072] The colorless and transparent liquid active silicone oil obtained in Example 7 of this invention was used to prepare potting compound for performance testing.

[0073] Raw materials for preparing the potting compound: 50 mPa·s terminal epoxy silicone oil (epoxy value 0.05), Wuhan Jiyesheng Chemical Co., Ltd.; spherical alumina, 50 μm, 10 μm, 2 μm, Qinghe County Chaotai Metal Materials Co., Ltd.; nano zinc oxide, Qinghe County Chaotai Metal Materials Co., Ltd.; polypropylene glycol diglycidyl ether, methyl hexahydrophthalic anhydride, tris-(dimethylaminomethyl)phenol, and Maclean's reagent.

[0074] Preparation process:

[0075] Compare with Example 1

[0076] Preparation of component A

[0077] 100 parts by weight of epoxy silicone oil with an epoxy value of 0.05, 400 parts by weight of 50μm spherical alumina, 150 parts by weight of 10μm spherical alumina, 70 parts by weight of 2μm spherical alumina, and 20 parts by weight of 200nm zinc oxide were stirred and mixed evenly in a high-speed disperser, and then milled three times in a three-roll mill. Finally, component A was placed in a vacuum oven and degassed at -0.0995MPa for 30 minutes at room temperature to obtain component A.

[0078] Preparation of component B

[0079] Add 30 parts by weight of polypropylene glycol diglycidyl ether, 30 parts by weight of methylhexahydrophthalic anhydride, and 0.2 parts by weight of tris-(dimethylaminomethyl)phenol to a mixer according to the proportions in the table. Mix and stir at room temperature for 30 minutes. After homogenization, filter through a 300-mesh screen and seal in a package to form component B.

[0080] Experimental Example 1

[0081] Unlike the control example, in component A, 95 parts by weight of terminal epoxy silicone oil with an epoxy value of 0.05 and 5 parts of the product of Example 7 were used instead of 100 parts of terminal epoxy silicone oil with an epoxy value of 0.05 in the control example.

[0082] Experiment Example 2

[0083] Unlike the control example, in component A, 90 parts by weight of 90 parts by weight of terminal epoxy silicone oil with an epoxy value of 0.05 and 10 parts by weight of the product of Example 7 were used instead of 100 parts by weight of terminal epoxy silicone oil with an epoxy value of 0.05 in the control example.

[0084] Experimental Example 3

[0085] Unlike the control example, 85 parts by weight of terminal epoxy silicone oil with an epoxy value of 0.05 and 15 parts of the product of Example 7 were used in component A instead of 100 parts by weight of terminal epoxy silicone oil with an epoxy value of 0.05 in the control example.

[0086] The comparative example and components A and B from the experimental example were mixed uniformly at room temperature at a mass ratio of 100:10, cured in an oven at 125℃ for 1 hour, and then their properties were tested. Viscosity was tested according to GB / T2794-2013, density according to GB / T533-208, thermal conductivity according to GB / T11205-2009, Shore A hardness according to GB / T531-1999, and tensile strength and elongation according to GB / T528-2009. Specific test data are shown in Table 1 below.

[0087] Table 1

[0088]

[0089] A comparison of Experimental Examples 1-3 and Control Example 1 reveals that as the amount of silicone oil product from this invention increases, the viscosity of the potting compound decreases, and the hardness after curing decreases, further proving that the single-active silicone oil with the desired properties is obtained in Example 7 of this invention.

[0090] Finally, the method of this invention is merely a preferred embodiment and is not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing 1,1,3,3,3-pentamethyldisiloxane, characterized in that, Includes the following steps: 1) Mix dimethylchlorosilane with long-chain alkylchlorosilane to obtain a mixture, add the mixture dropwise to water, and react at 35~40℃ for 1~2h after the addition is complete. After the reaction is completed, let it stand and separate the liquids. Take the upper layer and remove water and low boiling points. 2) Add hexamethyldisiloxane to the product obtained in step 1), rearrange it at 20~40℃ under the action of the first catalyst, filter it, and collect the fraction at 85~87℃ and 60cm Widmanstätten column by distillation; the first catalyst is concentrated sulfuric acid, solid acid or cation exchange resin. In step 1), the long-chain alkyl chlorosilane is dimethylpropyl chlorosilane, dimethyloctyl chlorosilane, or dimethyldecyl chlorosilane.

2. The preparation method according to claim 1, characterized in that, In step 1), the long-chain alkyl chlorosilane is dimethyl octyl chlorosilane.

3. The preparation method according to claim 1, characterized in that, In step 1), the molar ratio of dimethylchlorosilane to long-chain alkylchlorosilane is (1.1~1.3):(1.6~2.6), and the amount of water used is 75%~100% of the total mass of dimethylchlorosilane and long-chain alkylchlorosilane.

4. The preparation method according to claim 1, characterized in that, In step 1), the dropping rate of the mixture into the water is adjusted to control the temperature of the reaction system between 20 and 25°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that, In step 2), the first catalyst is solid acid HND-580; the amount of the first catalyst is 8-12% of the mass of hexamethyldisiloxane.

6. The preparation method according to any one of claims 1 to 4, characterized in that, In step 2), the molar ratio of hexamethyldisiloxane to dimethylchlorosilane is 1:(1.1~1.3).

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